I've been meaning to write this for a long time but I keep forgetting to do it.

I'd like it to be understood by all, that plugging the output of a phono stage into an amplifier or receiver input called phono might seem right to some, but is bloody stupid!

"Well, it's called a phono stage so I connected it to the input saying phono"

The phono input (if your amp/receiver has one) IS TO AN INTERNAL PHONO PREAMP!

I'm pretty sure all our instructions say not to do this, but who the hell reads instructions? Instructions fall into the same bracket as the Bible!

A phono stage equalises a magnetic cartridge, and also an RIAA record. By not understanding that you will not realise that a phono input then does the same again.

"Oh, the noise it's making. Your phono stage is faulty"

The phono stage has a gain of about 60dB (x1,000) at 20Hz (lowest bass), and the built-in phono stage does roughly the same.

The result? 120dB of lowest bass gain, that's times one million, which is one thousand squared.

At 1kHz (the mid reference frequency) it's usually around 40dB, so you get 80dB or ten thousand times, instead of one hundred (100 x 100 is 100 squared, which is 10,000).

At the highest audio frequency, 20kHz, the gain is normally about 20dB (that means 10), so here again we get double the dBs, that's 40dB, which means times 100, and 10 squared is 100, yes?

So one million times the output of a phono cartridge at 20Hz. What's that?

Well, the cartridge because of its constant velocity outputs 1/10th of its 1kHz output so if it's 5mV at 1kHz, it's 0.5mV at 20Hz.

So, one million times 0.5mV is half a million mVs. Which is 500 volts!

Now, admittedly you'll turn the volume down, and another little known thing is that no transistor amp can do 500 volts, and I'd be surprised if a domestic valve amp can do 500 volts r.m.s.

So it clips hard, and what do you get when it clips hard? A square wave!

So what you're getting is a square wave the size of the amp's front end power supply voltage.

"But it's crackling like crazy"

Well, of course it is!

"And the amp has shut down"

Well, that's it's protection circuit!

Or worse, "the fuses have all blown"

Well, what do you expect?!

I'll not bother explaining the mid and high frequency levels this causes, because hopefully it will have sunk in by now?

Plug the phono stage output into a line-level input like aux, and all will be fine.

The stupidest things I've ever done with hifi are connect speaker drivers directly to a laptop headphone socket with no amp (many years ago; damaged the laptop sound output over time but it was fun while it lasted) and connected headphones directly to Majestic line-out and a small pair of speaker drivers directly to Bitzie headphone output; no harm done but didn't perform as expected.